1. Field of the Invention
Embodiments of the invention generally relate to expanding tubulars in a wellbore. More particularly, embodiments of the invention relate to the expansion of tubulars below restrictions located in the wellbore. More particularly still, embodiments of the invention relate to an expandable tubular configured to be expanded below restrictions located in the wellbore.
2. Description of the Related Art
Oil & gas and other types of wells are completed by drilling a borehole in the earth and then lining the borehole with tubulars, such as liners, casing, or well pipe, to form a wellbore. Using apparatus known in the art, the tubulars are cemented into the wellbore by circulating cement into the annular area defined between the outer wall of the tubulars and the borehole. The combination of cement and tubulars strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the tubulars for the production of hydrocarbons.
Recent developments in the oil and gas exploration and extraction industries have included using expandable bore liners and casing. Apparatus and methods are emerging that permit tubulars to be expanded in situ. The most common expansion methods include the use of a cone, an expander tool with radially extendable members, or a hydraulic pressure introduced inside of the tubular, also know as hydroforming.
During the formation or after the completion of a wellbore, occasionally, a leak may develop at some point along a length of a tubular that permits the loss of well fluids into the surrounding environment behind the tubular or permits the introduction of unwanted fluids into the tubular and the wellbore. It is therefore sometimes necessary to seal or patch a hole or other defect in the tubular to prevent the loss or introduction of fluids through the wellbore. By utilizing the expansion techniques discussed above, an expandable patch or liner may be located adjacent a leak in the tubular and expanded into sealed engagement with the inside wall of the tubular to prevent further leakage.
There are several problems, however, associated with the expansion of tubulars in general. First, expandable tubulars are limited to an expansion of about 10%-25% of their original diameter using existing expansion practices. Second, as the expandable tubulars are subjected to higher pressures in the wellbore, the minimum wall thickness requirements for the expandable tubulars to resist collapse or burst forces exerted by these pressures significantly increase. Finally, the running tools and the expansion tools themselves continue to face strict dimensional limitations as the inner diameter of the wellbore typically decreases with increasing depth of the wellbore.
These problems are exacerbated when the expansion of tubulars may be utilized to address a defect below a restriction in the wellbore. A restriction may include downhole packers, safety valves, tool landing profiles, lubricators, etc. As mentioned above, these restrictions pose additional severe constraints in running standard expandable tools into the wellbore. These restrictions also demand the use of high expansion ratio expandable liners, which require high expansion forces. Further, smaller diameter wellbores require smaller diameter expandable tubulars, which geometrically leads to larger expansion ratios. Techniques like hydroforming or expandable packers require high pressure surface pumps or hydraulic intensifiers along with the high expansion ratio expandable liners. When using hydraulic pressure to expand a tubular, due to the high pressure required, weaknesses in the tubular are exploited limiting the amount of expansion that can be achieved before the tubular ruptures.
Scab liners and inflatable packers have been traditionally used to deal with leaks in a tubular since they can pass through restrictions and then expand to seal the leak area. The disadvantages of these devices include unreliable sealing and a considerable reduction in the flow area, which affects production of the well. Longitudinally corrugated pipes have also been proposed but connecting such pipes still remains a challenge.
Therefore, there is a need for a new and improved method and apparatus for expanding tubulars in a wellbore. There is also a need for a new and improved method and apparatus for expanding tubulars below restrictions in the wellbore.